The present invention generally relates to testing arrangements for VDSL based communication networks having combined video and data services, and more particularly to an arrangement for testing a physical VDSL network drop to a user location.
Digital Subscriber Line signal architectures, generally denoted as xDSL, allow digital distribution of combined broadband video and data services with traditional narrowband voice transmissions.
One form of xDSL of particular interest to the present invention is VDSL (Very high speed Digital Subscriber Line), which is a packet-based transmission architecture used to provide extremely high bandwidth distribution of digital video and data signals to customer buildings. A VDSL-based architecture can advantageously provide a single platform for supporting bandwidth-intensive applications, such as Internet access, remote LAN access, video conferencing, and video-on-demand.
ADSL or asymmetric digital subscriber line services generally use existing unshielded twisted pair (UTP) copper wires from a telephone company""s central office to the subscriber""s premise, utilize electronic equipment in the form of ADSL modems at both the central office and the subscriber""s premise, send highspeed digital signals up and down those copper wires, and send more information one way than the other. The ADSL flavor of xDSL services is capable of providing a downstream bandwidth of about 1.5 Mbps-8 Mbps, and an upstream bandwidth of about 16 Kbps-64 Kbps with loop distances ranging from about 3.7 km-5.5 km. HDSL or high bit rate digital subscriber line services provide a symmetric, high-performance connection over a shorter loop, and typically require two or three copper twisted pairs. HDSL is capable of providing both upstream and downstream bandwidth of about 1.5 Mbps, over loop distances of up to about 3.7 km. SDSL or single line digital subscriber line services provide a symmetric connection that matches HDSL performance using a single twisted pair, but operating over a shorter loop of up to about 3.0 km.
VDSL services are typically implemented in an asymmetric form having a downstream transmission capability of about 52 Mbps over twisted pair copper wire arranged in local loops of 300 m, 26 Mbps at 1,000 m, and 13 Mbps at 1,500 m. Upstream data rates in asymmetric implementations tend to range from about 1.6 Mbps to about 2.3 Mbps. A typical distribution system includes a central office equipped with a host digital terminal (HDT) and arranged to operate as a hub between multiple video information providers (VIPs)/digital service providers (DSPs) and customer residential dwellings. In a fiber-to-the-neighborhood (FTTN) type distribution system, optic fiber (e.g. OC-3c and OC-12c) lines are used to connect the central office to a universal system access multiplexer (USAM), which is then connected to a network interface device (NID) located on the customer property via twisted pair copper wire. A dedicated VDSL loop extends between the NID and an individual customer residence using an existing POTS or telephone system twisted pair wire, and a customer interface device, such as a residential gateway or set top box, provides a connection point for a customer television or personal computer. A fiber-to-the-curb (FTTC) type distribution system is similar except that a broadband network unit (BNU) is used in place of the USAM, and coaxial cable is used to connect the BNU, NID, and set top box.
The VDSL signal format is used to carry signals to and from the customer. In these systems, the central office provisions each user for programming access rights, and maintains a profile database for each provisioned customer at the HDT to control the signals/channels that can be viewed by the customer.
In this environment, each of the various components and connections play a critical role in maintaining signal and network integrity. One element of particular concern involves the network drop to each customer location. To date, a suitable test arrangement has yet to be developed which would allow each drop to be tested without actual provisioning of video/data service to the customer location. Because of service activation overhead and costs as well as potential theft of services concerns involved with having a drop be provisioned without verifying the drop""s ability to support quality signal distribution, a need exists for an economical arrangement for testing a physical drop to a customer site that does not require pre-provisioning of the drop.
Therefore, it is an object of the present invention to provide an xDSL/VDSL network test set and system capable of qualifying a customer drop without requiring the drop to be provisioned for receipt of services.
It is another object of the present invention to provide a VDSL network test set which allows a field technician to detect ATM cell loss and delay.
It is a further object of the present invention to provide a VDSL test system which allows verification of proper receipt of video/data signals at a customer NID, as well as out signaling capability for change of channel commands.
It is yet another object of the present invention to provide an economical VDSL test set which can be used by a field technician to pre-provision test a customer drop, as well as provide post fault network isolation.
In accordance with these and other objects, the present invention provides a system for testing performance capability of a user drop in an xDSL-based video and data communication network includes a network video signal test source and a network data signal test source arranged to generate at least one video test channel and one data test line. The network includes a signal processing arrangement for converting the test signals to an xDSL format for transmission on a network cable. A test device is coupled to the user drop and is provided with a network sign-on identifier for identifying the device as a test device. A network entitlement controller is arranged to provision user drops for receipt of video programming and data from a network distribution system. The network entitlement controller arranged to provision an unprovisioned customer drop for receipt of the network video test channel and the network data test line in response to receipt of a test device sign-on identifier, wherein the test device is arranged to test the user drop for video signal quality, and data transfer rate, error and loss conditions based on the generated test signals.
In accordance with one aspect of the present invention, the test device is formed as a modified user et top box. The video signal quality is determined by connecting a video monitoring device such as a television to an output of the test device. Alternatively, indicator lights can be provided on the test device to provide an indication of signal quality. The data transfer rate, error and loss conditions can be tested by connecting a suitably programmed computer to an output of the test device, or by incorporating such a microprocessor based system in the test device itself.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.